Figure 2. Cellular tension is affected when DRhoGEF2 expression levels are modified.

(A–L) Amnioserosa mechanical response after ablation of a single cell. (A), (E) and (I) are confocal images from stage 13 embryos of wild-type, RhoGEF2 GLC and RhoGEF2 overexpression, respectively, before ablation. Dashed line represents the position of the line scanned repeatedly and used to build the kymographs (C, G and K). In (A), (E), (I), (D), (H) and (L) the crosshair indicates the ablated cell whereas in (C), (G) and (K) indicates the ablation time. (B), (F) and (J) are images from the same embryos taken after ablation of a single amnioserosa cell. (D), (H) and (L) are overlays of cell edges before (Red) and after (Green) ablation to illustrate each cell's recoil. (M) Mean recoil displacements for WT (blue), DRhoGEF2 overexpression (black) and DRhoGEF2 maternal mutants (red). The shaded areas represent the standard deviations. Displacement axis is in microns and time axis is in seconds. Note the higher SD in DRhoGEF2 overexpression (grey) compared with WT (yellow) and maternal mutants of DRhoGEF2 (pink). v₀ = initial recoil velocity; higher values indicate either more tension or less viscosity D = coefficient in power-law fit; higher values indicate either more tension or less stiffness α = power-law exponent; higher values indicate a more fluid tissue (lower values a more solid tissue) v ₀ was determined via a linear fit to the first 100 ms of recoil. D and α were determined via a power-law fit to the first 5 s of recoil.